一、变异与演化 (一)寄生虫演化关系的实用意义 追溯演化关系的目的在于了解“类”或“群”之间的亲缘关系,充分反映其间的本质联系,深化“同”“异”程度的认识。应该指出,系统分类学上的等级制,即 First, the variation and evolution (a) the practical significance of the relationship between the evolution of parasites The purpose of retrospective evolutionary relationship is to understand the “kinds” or “groups” of the kinship, fully reflect the essential links between them, and deepen the “same” “exact” degree Awareness. It should be pointed out that the systematic taxonomic hierarchy, ie